Performance analysis of frequency-hopped spread spectrum packet radio network under the Poisson approximation

The throughput performance of the unslotted spread-spectrum packet radio network (SS PRN) is approximated. The approximation assumes that the number of errors in a received packet is Poisson distributed. Two channel access protocols are considered: ALOHA and a channel load sensing protocol. A simple bound on the error of the Poisson approximation is derived for both channel access schemes. Simulations were performed to verify the accuracy of this approach. It was found that the Poisson approximation improves with increasing processing gain and packet lengths. For a packet length of 1027 b and a processing gain of 1000, the difference between simulation and approximation results was not noticeable. It is concluded that the Poisson approximation can be used to quickly and accurately compute the throughput performance of FH/SSMA systems with FEC (forward error correction) coding when the processing gain is high